1. Field of the Invention
The present invention relates to an electric punch for punching holes in documents and other sheet materials for filing, particularly to an electric punch enabling the hole spacing to be selectively set at 70 mm or 80 mm merely by changing the position of constituent components.
2. Description of Related Art
Punches are commonly used as perforating devices for forming holes in documents and other sheet materials to be filed. Both manual and electric (electrically powered) punches are available. Although the manual punch is more widely used, it requires considerable force to operate when punching a thick stack of sheets and also requires the center of each stack in the binding direction to be marked by creasing the uppermost document at the middle. The electric punch is more convenient because it can carry out punching automatically driven by electric power. A typical electric punch is the one taught by Japanese Patent No. 1967332.
The electric punch taught by this patent has a main frame that is equipped with left and right punch holes and under the punch holes with a catcher for collecting chad (punchings) and is formed at its left and right portions with guide holes that communicate with the left and right punch holes. The electric punch further has left and right supports, each having an insertion slot for paper sheet insertion, that are installed between the left and right guide holes and punch holes; left and right perforating members installed to be vertically movable within the guide holes of the left and right supports and having perforating blades at their lower ends; left and right operating arms extending fore to aft that are mounted at upper portions of the left and right supports to be vertically swingable and that rotatably support the upper ends of the left and right perforating members at their forward ends; and a rotating shaft that is mounted on the main frame to extend laterally, is rotated by the output of an electric motor and rotates the left and right operating arms to swing vertically. The left and right operating arms are formed at their rear side portions with long guide grooves that are long in the fore-aft direction. The operating arm on one side is formed at the front top of its long guide groove with a guide slot that communicates with the long guide groove. The rotating shaft has rotating disks attached to its opposite ends. Operating pins rotatably inserted in the long guide grooves are provided to project axially from eccentric positions of the right and left rotating disks with their phases offset in the rotating direction of the rotating disks. One operating pin is engaged with the guide slot communicating with the long guide groove of the operating arm on one side to put the perforating blade of one perforating member in standby state above the insertion slot. The other operating pin is inserted in the long guide groove of the operating arm at a midway position thereof to put the perforating blade of the other perforating member in standby state above the insertion slot.
One disadvantage of this conventional electric punch is its large size, which makes it heavy and difficult to carry about. Another is that while the spacing between the punched holes can be set at 70 mm or 80 mm, this requires a spacer (a separate component) to be fitted on the rotating shaft for width adjustment, which involves extensive disassembly.
A need has therefore been felt for an electric punch that is compact and light in weight and enables the hole spacing to be changed with ease.
The object of the present invention is to overcome the foregoing problems by providing a thin, compact and lightweight electric punch that utilizes bent perforating member operating arms to enable selective setting of the punched hole spacing at 70 mm or 80 mm by exchanging the left and right operating arms, without utilizing any separate component.
In order to achieve the above purpose, the present invention provides an electric punch comprising: a drive section; left and right perforating members installed on opposite sides of the drive section each including a perforating blade and an operating arm; punch holes for passage of the perforating members; and at least one chad catcher for collecting punchings produced by the perforating members; the electric punch being adapted to punch two holes in a stack of sheets inserted between the perforating members and the punch holes, wherein: a bend is formed midway of the length of the operating arm of each perforating member so that forward and rearward portions of the operating arm are laterally offset in parallel by a prescribed distance and the operating arms are clamped with two supports of different width, thereby enabling punched hole spacing to be selectively set at 70 mm (U.S. standard) and 80 mm (European and Japanese standard) by exchanging the left perforating member and the right perforating member.
The operating arms can be constituted as long and slender plate members bent into a crank-like shape. Moreover, the operating arms can be given a length nearly equal to that of the electric punch and the diameter of the rotating disks can be made small.
A configuration can be adopted wherein the center-to-center spacing between the punch holes of the perforating members can be set at either 70 mm (U.S. standard) or 80 mm (European and Japanese standard) by moving each of the left and right perforating members 40 to the opposite side of the drive section. Engagement members for engaging long holes of the operating arms can be provided to project from right and left rotating disks at identical phase locations to enable simultaneous initiation of punching operation and simultaneous hole punching on the left and right sides.
Since the electric punch according to the present invention thus makes it possible to exchange the right and left operating arms and their associated supports, it enables the spacing between the punched holes to be changed between 70 mm (U.S. standard) and 80 mm (European and Japanese standard) without need for any additional component. A thin, compact and lightweight electric punch can be provided by locating the drive section at the center, maximizing the length of the operating arms, and minimizing the diameter of the rotating disks.